[Nitric oxide is involved in the modulation of central respiratory rhythm].

This experiment was expected to test whether nitric oxide (NO) exerted significant effect on the central respiratory rhythm. Experiments were performed on in vitro brainstem slice preparations from neonatal rats. These preparations include the medial region of the nucleus retrofacialis (mNRF); a part of pre-Bötinger complex, ventral respiratory group (VRG) and dorsal respiratory group (DRG). Respiratory-related burst activities were recorded from hypoglossal nerve rootlets before and during superfusion of the slice preparation with L-Arginine (L-Arg), sodium nitroprusside (SNP) or 7-nitro indazole (7-NI, an inhibitor of NO synthase). After perfusion with L-Arg and SNP, there was no significant change in respiratory rhythmical discharge activity (RRDA), but 7-NI decreased the integral amplitude of burst and inspiratory time. These results indicate that NO may take part in the inspiratory off-switching mechanism and that it also modulates the amplitude of respiratory-related bursts.